First, they tilt their upper body
back and forth like an inverted pendulum action. Instead, the
upper body and head should not tilt. Horizontal action is okay,
but tilting is bad.

The next big mistake is not getting
the hip action. As each knee bends, the same hip must be allowed
to drop. You can't dance correctly if you shuffle your feet.
Instead, you must make complete weight changes with each step.